Electrical apparatus



Feb. 7, 1928.

C. A. HOXIE ELECTRICAL APPARATUS Original Filed Obi.

29, 1920 4 Sheets-Sheet l Fig. 12.

Im/entor'. Char-es /\.Ho ic, by His Attorney- Feb. 7, 1928. 1,658,680

c. A. HOXIE ELECTRICAL APPARATUS Original Filed Oct. 29. 1920 4 Sheets-Sheet 2 Fig 2. v

Feb. 7, 1928. 1,658,680

C. A. HOXIE ELECTRI CAL APPARATUS Original Filed Oct. 29. 1920 4 Sheets-Sheet 3 Fig].

Inventor;- Charles A.Ho :e

Feb. 7, 1928.

C. A. HQXIE ELECTRICAL APPARATUS Original Filed Oct. 29. 20 4 Sheets-Sheet 4 Inventor: Charles A.Hoxie, by a 2%? His Attorney.

Patented Feb. 7, 192a.

onr innns A. zioxrn, on

GTADY, Hill? YGRK, ASSIGTTCB TO GENERAL ELECTRIC COMPANY, A CORIEORATION OF NEW YORK.

nLnc'rnIoAL original application filed fietooer 2 9, 1920, Serial No. 420, l91.

October 10, was.

My present invention, which is a division or" my application, Serial No. lQOAQl, filed (Jet. 29, 1920,'relates to apparatus for selectively receiving? and making a record of small current impulses and more particularly for recording photographically 1mpulses corresponding to rapidly transmitted signals.

In my Patent- No. 1,456,595, issued May 29, 1923, I have described an apparatus for receiving radio signals. the same comprising means for causing;- a current whose variations correspond to the signals received to traverse a series of coils which surround a vibratory reed or diaphragm of man'nctic material. This reed or diaphragm is supported between the poles of LWO permanent magnets in such a manner that by varying tlic'magnetic field produced by the currents in the coils the diaphragm is causet to virate. deans is provided to adjust the tension of the diaphragm to cause it toa'ssuine a natural period of vibration corresponding to the period of the received signals. It was found that the disturbing effects dueto stray impulses could be eliminated to a large extent by operating with frequencies above 1-500 and tuning the diaphragm accordingly. My present invention seeks still further to eliminate these disturbing effects by introducing in shunt to the operatin coils :tor the magnetic diaphragm what may be termed a tone trap. This comprises an inductance and capacity, each of which is connected across the operatinp coils and which together may be adjusted so that the local c" uit in which they are included may be tuned to a frequency correponding; to that of the signals received.

One object of the present invention is to provide an improved receiving system wherein an alternating current whose intensity corresponds to the received signals is rectified and alternate rectified impulses are passed through each of two coils surrounding the diaphra 'ni of the o'alvanometer in such manner that the effect of each impulse is to more .1238 diaphragm in the same direction.

Other objects and advantages of my in- AIEPARATUS.

Divided and this application filed Serial No. 593,615.

vention will appear as the description proceeds. I

to the accompanying drawings, -d view of an apparatus emv 'on with the end wall ren. wing the reflecting galvanommounting,

thesource of light and 2 IS a plan view 9 Q) ranometer and its mounting; Fig. led View of a mounting of the m ter ad usting rod; Fig. i is a ti e iew of a portion of the vibrai iwgm of th galvanoineter and the mirror and its mounting; 5 is om plan view, showing a poi ture disclosed in Fig. 41:; o is an end view of the galvanometer, certain of parts being shown in a section on the me 11-4 a ile view Lot 2; Fig. 7 is at the galvanometer, certain of the parts he shown in a section taken on the line t 2; 8 is an enlarged dep 2111 or the condensing lenses and its supinp; lraclret; Fig. 9 is a diagranmatic view of :1V receiving; circuit with the galvanometer connected thereto; Fig. 10 shows a Section of photographic record produced i apparatus employing the receiving circui. shown Fig. 9: 11 is a diaerainmat. view oi a modified form of receiving cir cult; Fin. 12 shows section of photographic record produced by apparatus employ ngthe receiving circuit shown 11: and I 13 is a view similar to Fia'. ll but showinn' .jtied circuit arrangement. Referring to Fig. 1 of the drawi: represents a lie-ht proof ca ing provided w a lower chamber 11 which contains the n vanometer. This 9a vanoiueter which 'ill be more particularly desciibed hereafter is mounted upon trunnions 13 pivoted in brackets 14 extending from the sides of the supporting plate 15. The galvanometer m ay be turned in a horizontal plane on the 'r nions 18 by operation of the screw 15 is pivoted at 3% to the base 1'? and may be turned in a vertical plane on the pivot by rotation of the rod 18. This rod is loosely coupled to the bracket 19i ormed on the supporting plate 15 and is threaded to a collar formed on the outer end of the shaft 21 (see Fi 3 of the drawing). Shaft 21 is pivotally mounted in a bearing 22 and is prevented from moving; longitudinally in the hearing by engagement of a screw 23 with the walls ofan annular groove 24 formed in the shaft 21; The upper portion of the casing A is formed with an enlarged portion 25 divided at its center by a partition 26 into two compartments 2? and 28. In compartment 27 are located two incan descent lamps 28 and 29 and across the bottom of this compartment is secured a plate 30 provided'with openings 31 and 32,111 the compartment 28 is the cylindrical lens 33. One of the sources of light in the compartment 2'? is employed to furnish the op erating beam to tr ce the desired curve upon the; photographic tape. The other source of light is applied for the purpose of indicating theposition of the galvanoinetei' and also to enable-the operator to make the necessary adjustments in the receiving circuit to insure the proper recording of the signals The beam of light from this latter source is reflected from the galvanometermirror through a spherical lens (not shown) which is located-in proximity to the reflecting mirror onto a ground glass plate located at the top of the casing A and by the position of the spotof light on this plate the operator is enabled to ascertain the adjustment of the galvanometer. This indicating means is clearly disclosed in my prior application above referred to and as the same forms no part of the present invention. it will not be further described. The photographic tape or film may by suitable apparatus which is described in the parent application, be fed along continuously and exposed to the beam 7 of light from the source 28.

In Fig. 9 I have indicated a wii'eless'receivmg apparatus which comprises a vacuum tube detector having coupled to its grid circuit'il an antenna circuit 1 2. included in the plate circuit of the vacuum tube device is the source '73. the variable inductance at and in parallel with. the inductance the condenser 75. Bridging this lilflllCtill'lCOllllCl condenser are the coils 76, 7'1 and 78 of the galvanometer. 'lhesecoils are arranged in series and the middle coil is wound: to ope pose the end coils as shown in the drawing.

79 and .80 are two permanent magnets and '81 1s a metallic reed or diaphragm secured at its ends and extending between the poles ofthe permanent magnets. Coils 76, 77 and 78 surround the diaphragm 81 and when current is flowino therethrounh serve to produce inthe diaphragm consequent north and south poles'as is indicated in the drawing.

The permanent magnets are arranged so.

that opposite poles occur on the same sides.

Attached to the dia-' of the diaphragm. phra gm and movable the ew 1s a mir or 82 which serves to reflect. the light from the source 28 onto the moving tape.

lmpulsesreceived inthe antenna clrcuit cause a varyingpotential to be applied to the grid of the vacuum tube dev1ce 70 and this produces acorresponding change in the vcurrent of the plate circuit which includes whichis attacheduthereto andthe reflected";

beam of light from the source28 which acts l certain of the i The movement CII upon the photographic tape to produce when r the tape is developed a line of the form similar tot-hat shown in EigxlO. By means hereinafter to he described the tension of' the diaphragm 81 is adjustedso that its natural rate of vibratloncorresponds to the frequency ofthe waves which it is desirec toreceive. v V

I have found that it is desirable that the rate of vibration of the diaphragm be as high as it may conveniently be made. EX-

periments have shown that when the dia* phragm vibrates at a frequency of 2000 cycles per second, the effect of stray atmospheric impulses or the so-called static is very much less than when the diaphragm is vibrated at the'rate of 1200 per second.

The elimination of the eilectof static on the vibration of the diaphragm 81 is further increased by the particular arrangement and adjustment of thereceiving circuits herein disclosed. The inductance 7 L and-the capacity Y5 should be so adjusted that the local circuit in which they are .included'is reso nant to the frequency of the current pro 'duced in. the plate circuit by the signals.

T his results in a much greater portion of the current of signalling frequency passing tlufough the coils 76. T7 and 78 than through the inductances and capacity whereas ourrents of less frequency are almost entirely short circuited bythe inductance and capacity and therefore do not have an appreciable intiiuence onthe coils of the galvanometer.

In choosing the proper values-f0 r i nductance and capacity t has been found necessary to use a rather small capacity and, a large inductance; the latter preferably having as small tL lQSlSiftllCQ as'possible. In this arrangement it ES to be notedthat'the vacuum tube and battery 73 act as'asource of ourno 11" v 'nry' j 0' 1 1n, 0 t d .cnt uln a u n im er ancc. L nsin .uc tance 7% acts a short circuit for the direct current component of the plate eurrenh 1:

Referring particularly to Figs. 2, 6 and 7, the reflecting galvanometer which I propose to use preferably comprises a base member 160 formed with two uprights 161. Secured to these uprights by screws 162 is a top plate 163 formed with end strengthening ribs 16% and a central. slot 165. Depending from the plate and guided by the slot 165 are supports for the permanent magnets 79 and 80. These supports comprise blocks 166 upon which are secured guide strips 167 by means of screw 16%. Screws 169, provided with washers. serve to retain the guide strips 167 within the slots 165. Each of the magnets is clamped between blocks 170 and 171 by means of a belt which passes through both blochsinto block 166. Screws 172 mounted in the ends of blocks 166 and formed with disc-shaped engagemen s 173 adapted to project within slots 11 d in the plate 163 serve to provide means for moving the magnets 79 and toward or away from one another. These magnets are each formed of a bar of steel of rectangular cross section and bent as outlined in dotted lines in Fig. 2. Sheet metal pole pieces 175 which are secured to the ends of the bars extend downwardly and are provided with lateral oit'set portions arranged to lie in close proximity to the diaphragm 81. This diaphragm is securely held between lips 17 6 formed at the ends of mernhers 17?. Members 177 are arranged to slide in openings 178 formed in the uprights 161 Adjusteb le screws 179 engage threaded openlnq's 166 lormed in the ends of the members hese screws are provided with operatin ieads 181 formed with hearing surit- 0; adapted to engage the outer faces 0 the upri hts In practice the tension of the diaphragm 81 w ll be adjusted so that its natural period of vibration will correspond t the frequen y of the eurrent'to be recorded. As so constructed the lines of stress set up in said diaphragm by vibrations are substantiully all in the same direction. Surl' g the diaphragm are the coils 76,77 and 78 suitably mounted upon sheet metal clips. All supporting parts for the dia pl in. cells and permanent magnets are pr "b termed of brass. Connected to :gm 61 by means of members 183 and 18 i is a triangular shaft 185 of magnetic material. See Figs. i and 5. The end Oil the member 18st is flattenedat 186 Where it is so :ured to the shaft 185 so as to provide in effect a flexible connection therewith which will permit the shaft to rotate about its bearings without any lost mot-ion. Shaft 185 is held against V-shapecl jeweled bearings 187 by means of a permanent magnet 188, these hearings being formed adjacent the poles of the magnet. ror 82 which serves to reflectthe beams of light from the sources 28 and 29 is mounted upon thesha-ft A 9 6??? 9Q L y screws teflis Printer of th t base 160 is provided with suitable openings for the passage of the incident and reflected beams of light.

In F 11 which shows a modified form receiving cire hern'iionic vacuu o the primary 5 al of the no er 41 1 is conuecter ti rough the co 262 and resistance 203 to the grid i the vacuum tube device 205 and through the battery 206 to the grid 207 of the vac- M1111 tube 'ce 208. other lcrr l .i of the secondary of the t rc-rmer is coueclcd to one terminal 0 uch oi the hr. 80

, .i and 5310. The lied with heating current is connected to '.l

ats are suit a batter arranged. upon op 390 site sides of the diaphragm. Adj-am north and south poles are positioned I close proximity to the central portion of diaphragm. The remaining north aiul south poles are not active in pr ducing movement of the diaphragm.

Alter-nations of current in the tra or 201 produce changes of potential grid 20%, 207. This results in pul' or intermittent flow of direct current the filament 209, 216 to tl and through the coil 215. nometer, each impulse 01' c1, to create a mae etic pole oi? the at the center or the diaphra m]. Du]... time when the flow oi current 'illlOll t vacuum tube device 2365 and coil i minimum, the potential of tl the vacuum device 208 Mom the filament 210 to plate 2l6 and throiw'h coil 21'? of the galvanometcr. This di rence phase of the plate currents tl rough two vacuum devices is due to the presence of the battery Q06 in the circuit to the grid 20? which has the etlect of maintaining the grid 207 at an initially diiierent poten ial from that or" the grid 1 The cl fore of an alternat galvanometer diaphragm to be uniformly urged toward one of the poles of the permanent magnets 221 or 222. A change in the amplitude of the alternations in the primary circuit or the transformer due to the reception'ot signals results in a change in the intensity of the intermittent or pulsating current through the platecircuits of the vacuum tube devices 205 and 208 with the result thatthe intensity of themagnetic pole formed by these-currents through the coils 215 and 217 is changed and the diaphragm is urged toward one of the poles of the permanent magnets by a force of greater or less intensitythan before. The

' diaphragm will thereforeassume a different paratus when the diaphragm position and the reflected beam will be moved to form upon the tape an impression corresponding to the signal received. In this form of receiving apparatus it is desirable to have the galvanometer dead beat and for this purpose the tension of the diaphragm should be adjusted so that it is out of tune with the frequency of the receiving signal. I have'tound with this type of apadjusted to the frequency of approximately 2000 and the frequency of the incoming signals from to higher that the signals are clearly recorded at a rate otapproximately 600 words per minute and this through extremely bad static conditions. The character of record made by the apparatus with the type of receiving circuit disclosed in Fig. 11 is shown in Fig. 12. V

:Fig. 13 shows the somewhat simplified form of circuit arrangement in which but a single galvanometer coil is employed. The coil 250 is connected from the plate 251 of the thermionic vacuum tube device 252 to. an adjustable contact 253 adapted to moveover a resistance 25%- which latter is connected to opposite terminals of the'battery 255. A resistance 256 is connected between the battery 255 and plate 251, as shown. From the drawing it will be seen that coil 250 in effect constitutes the bridge circuit of a wheatstone bridge of which two of the legs are the path through the ther mionic device 252 and the lower portionot the resistance 25% and the remaining two legs are the resistance and the upper portion of the rciustance It is obvious that the current which 7111 the form of apparatus, shown in Fig. 9,

passes through the galvanoineter coils T6, T7 and'78 may be rectified and thei'ice passes around the diaphragm in the manner shown in Figs. 11 or 13. I

What Iclaim as new and desire to secure by Letters Patentof the United States, is, 1. lhe combination in a signal receiving system of a thermionic vacuum tube device so connected that audio frequency signaling currents will be produced in its output cir-.

phragm, and an adjustableinductance and capacity each connected in shunt to said coilsian'd adapted to be tuned to the same frequency as that of the diaphragm. I 2. In an' electrical apparatus,'a movable ,magnetic member arranged in a magnetic field, two coils arranged end to end and surrounding said magnetic member, two thermia plate, grid and filament, a source of current, connection from each of the plates to anouter end of each of said coils, a connec tion from said sourceot current to the inner end of each of said coils, aconnec'tion from said source to said filaments, means for iin pressing an alternating potential upon the grids of each or said thermionic devices and a source of potential included in the circuit to one of said grids. V a

3. T he combination of a thermionic vacuum tube device having grid andplate, means for impressing upon the grid varying potentials corresponding to the signals received, a transformer, the primary of which is in circuit with said plate, a second vacuum tubedevicehaving a grid, plate and'filament, the grid of said second device being connected to one terminal of the secondary onicvacuum tube devices each ot-which have of said transformer, a third vacuum tube device havinggrid, plate, and filament, the grid of said third device being likewise connected to the above m'entionedterminal ot the secondary of said transformer, a-source of potential included in the circuit to said last named grid, one terminal of each of said filaments being connected together and to the other terminal of thesecondary of said transformer, an indicating device comprising a vibratorymagnetic member arranged ina permanent magnetic field, oppositely wound coils surrounding said magnetic member'and arranged end to end" the outer terminals of each of said. coils being connected to each'ot the plates ol'said second and third devices, anda connectionbetween the. intermediate point'o'i said coils and the other terminals oi? each of said filaments, said last made connection including a source oi curprising a movable magnetic member arranged in. a permanent magnetic'field, coils surrounding said magnetic member and arranged end to end, one of said coils arranged in the plate circuit ofone of said thermionic vacuum devices and the other coil arranged in the plate circuit of the other of said thermionic tube devices and means for impressing upon the grid circuits of said thermionic vacuum tube devices alternating potentials Whose amplitude corresponds to the impulses it is desired to record, and means in the grid circuitof one of said vacuum tube devices for impressing thereon an additional potential.

In Witness whereof I have hereunto set my hand this 9th day of October, 1922.

CHARLES A. HOXIE. 

